When designing for both on-road automotive and off-highway machinery applications it is desirable to have a clear and accurate understanding of the duty cycle to which the drivetrain of a specific machine or population of machines is exposed. While a knowledge of the expected range of drivetrain torques and speeds is generally helpful to the design process, it is the amount of time the system spends under various combinations of torque and speed conditions—the “duty cycle”—that primarily determines the degree of damage that drivetrain components incur over the life of the machine.
A significant problem facing mechanical designers and equipment manufacturers today is a lack of comprehensive and accurate off-highway vehicle drivetrain duty cycle information. This situation owes to several factors. Production and operation of experimental machines from which duty cycle data may be collected is costly. The cost of instrumenting test machines for the purposes of duty cycle collection is usually high. The number of experimental machines is typically low, the test periods are usually brief, and test operators are usually few, thus limiting both the quantity and breadth of data available. Obtaining data from customer-owned machines has drawbacks and is often difficult with past instrumentation and data collection methods. Drivetrain laboratory test installations can introduce inaccuracies since overall system dynamics specific to the vehicle cannot be easily replicated with high fidelity in a lab environment. Hence, duty cycles are at best estimates, and at worst guesses, with the general result that drivetrains are overdesigned and over-tested. Without accurate duty cycle data there is also a risk that the drivetrain design or validation testing may fail to account for conditions arising from unforeseen applications of the machine.
A secondary problem is the desire to estimate the remaining life of key mechanical components within the drivetrain on an individual vehicle and to make that data available to the operator or a service technician. Remaining life calculations cannot be done without the ability to collect and store accurate and comprehensive duty cycle data.
Understanding the duty cycle of drivetrain components can be used to inform design and/or maintenance decisions for key individual components of the drivetrain that are subject to fatigue and wear (e.g. gears, bearings). When machine drivetrain duty cycle information is known prior to designing the drivetrain for a new or similar machine, it can be beneficial in numerous ways, for example, to reduce or eliminate drivetrain design and test iterations, to appropriately size individual drivetrain components, to appropriately tailor laboratory durability and reliability testing, etc. When machine drivetrain duty cycle information is known during the period when a machine is produced and sold, it can also be beneficial in numerous ways, for example, to increase machine uptime, to decrease warranty claims and associated costs, to identify individual machines in a population having a high rate of change in damage figures, to plan and schedule maintenance in advance (prognostics/predictive maintenance), etc.
It would be desirable to have a system and method for collecting and processing drivetrain duty cycle information by an onboard system during vehicle usage.